4H-SiC BJT Characterization at High Current High Voltage

In this paper, a model that can perfectly describe the experiment results was developed. Based on the model, detailed analysis showed that the defect at the base-emitter epi-interface is the key factor that limits today´s SiC BJT gain. The effect of emitter size also can be studied for SiC BJT. 1200 V SiC BJT under study can operate at bus voltage as high as 700 V. Until now, no such characterization has been made. In this paper, static and switching characteristics of 1200 V SiC BJT at high current and high voltage are reported for the first time. The common emitter output characteristics with current up to 28 A (1244 A/cm²) and the dynamic characteristics at a bus voltage of 700 V and high load current were obtained. Turn off loss and turn off time as the function of turn off current was recorded, which showed that the turn off loss of SiC BJT is much smaller than Si IGBT. Experiments showed an extremely large RBSOA of SiC BJT. With zero voltage base drive, the SiC BJT can successfully turn off 2.7 MW/cm² power density. No second breakdown was observed which is the most unattractive aspect of Si BJT. All these experiments prove that, unlike Si BJT, SiC BJT is a good competitor to Si IGBT